In deep coal mining, concepts have been developed to provide power system which perform functions such as conductor supply and/or load side potential measuring and fault current monitory and actuation of a switch device when certain conditions occur. See Record of the Industry Applications Conference (IAS), Orlando, Oct. 8-122, 1995, Vol. 3, Oct. 3, 1995, IEEE, pp. 2009-2012, XP000547126, Novak, T., et al., "Technological Innovations in Deep Coal Mine Power Systems," esp. FIG. 1).
V-E 0100 defines a TT network as a type of network in which overcurrent-, fault-current- and fault-voltage-operated protective devices can be used. TN networks are the most common, with overcurrent- and fault-current-operated protective devices being used. All elements are connected by means of a separate conductor, the PE conductor, which performs the protective function. Even though national and international regulations exist for setting up and testing electrical power systems, it is occasionally not possible in practice to prevent power systems from demonstrating deficiencies that can result in accidents or fire. In most cases, effective protection could be provided by using fault-current-operated protective devices, especially with low rated fault currents of 30 mA or 10 mA. However, these types of protective devices are not yet prescribed nationally or internationally for all fields of application.
According to current concepts in structural systems engineering, opening and closing commands can be supplied to specially designed receptacles via a bus. These types of switching commands may result in dependence on measurement results and information processing systems See e.g., (German Patent No. U-9 312 528). In this regard, certain functions, such as current-limiting functions, can even be transferred to the receptacle, which are then referred to as intelligent receptacles. German Patent No. 4 425 876 describes an intelligent receptacle of this type which includes a connector which has a bus interface. Here, the power line is used as the bus.
Other concepts provide the receptacles with child-proof mechanisms, or mechanical latches, which provide access to the current-conducting leads only when a suitable plug is inserted.